The Senate Judiciary Committee approved a Democratic bill calling for background checks on all gun sales, which could potentially lead to the biggest change in U.S. gun laws in years.

But the likelihood of the full Senate approving such a bill is slim because of objections from Republicans.

The bill was approved on a 10-8 party-line vote and mandates background checks on all gun purchases and sales, including private transactions. State governments will also be able to tap into a national criminal background check system.

But the most controversial proposal facing the panel — a ban on assault weapons — was postponed because its main proponent, Sen. Diannne Feinstein (D-Calif.), was not able to attend Tuesday’s hearing. That vote has now been moved to Thursday.

The Judiciary Committee also approved a measure by Sen. Barbara Boxer (D-Calif.) to boost funding for school security.

The background checks proposal, offered by Sen. Chuck Schumer, is only a “placeholder” while the New York Democrat — along with Sen. Joe Manchin (D-W.Va.) — seeks out Republicans to sign onto a bipartisan version. Schumer and Manchin hope to offer that compromise agreement once a gun-control package comes to the Senate floor in coming weeks.

“I remain optimistic we’ll be able to roll one out,” Schumer said of the bipartisan negotiations. Schumer and Manchin negotiated with Sen. Tom Coburn (R-Okla.) on the proposal for weeks, only to see Coburn end the talks last week. The two Democrats are still…